This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Viral capsids are composed of multiples copies of one or a few coat protein subunits. Knowledge on the extent of interactions of a capsid protein subunit in native and sometimes in non-native capsid environments will be of importance in understanding the relationship between the protein building block and the capsid size and architecture. Furthermore, the extent of similarity in the bonding and interactions of the subunits would point to the quasi-equivalences of subunits in viral capsids. The knowledge on the relationship between the type of the protein and the resulting capsid would aid in designing new and novel capsids. The objective of this project is to come up with measures/properties that would quantify the extent to which a subunit is involved in the protein-protein interactions.